Apparatus for inverting flow in a conduit

ABSTRACT

A flow exchanging device and a process using the same for diverting a fluid flowing on the periphery of a conduit towards the center thereof and simultaneously diverting a second fluid flowing in the center of the conduit to the periphery thereof, such device being an open tapered pipe having a plurality of openings on its walls and protruding lips around each of the openings for diverting the peripheral flow towards the center of the conduit. The center flow is diverted to the periphery through the wall openings. The device is particular adapted to use in the spinning of cellulose films from two qualities of viscose.

Charles-Messance Apr. 9, 1974 APPARATUS FOR INVERTING FLOW IN A CONDUIT[75] Inventor: Francois Charles-Messance,

Mantes-laJolie, France [73] Assignee: La Cellophane, Paris, France 22Filed: June 21, 1972 [21] Appl. No.: 264,859

[30] Foreign Application Priority Data June 29, 1971 France .7 l .2358L[52] US. Cl. 259/4 [51] Int. Cl B0lf 15/02 [58] Field of Search 259/4,18, 36; 425/198 [56] References Cited UNITED STATES PATENTS 3,402,9169/1968 Kates 259/4 3,427,002 2/1969 Wilding 259/4 3,697,051 10/1972Lachman 259/18 3,701,619 10/1972 Appeldoorn 425/198 PrimaryExaminer-Robert W. Jenkins Attorney, Agent, or Firm-Sherman & Shalloway[5 7] ABSTRACT A flow exchanging device and a process using the same fordiverting a fluid flowing on the periphery of a conduit towards thecenter thereof and simultaneously diverting a second fluid flowing inthe center of the conduit to the periphery thereof, such device being anopen tapered pipe having a plurality of openings on its walls andprotruding lips around each of the openings for diverting the peripheralflow towards the center of the conduit. The center flow is diverted tothe periphery through the wall openings. The device is particularadapted to use in the spinning of cellulose films from two qualities ofviscose.

7 Claims, 2 Drawing Figures APPARATUS FOR INVERTING FLOW IN A CONDUITFIELD OF THE INVENTION BACKGROUND OF THE INVENTION It is known thattransparent films of regenerated cellulose, widely marketed under thetrademark fCellophane are obtained by continuous extrusion of a causticsolution of viscose through the slit of a hopper into an acidregeneration bath where the film coagulates.

In the apparatus presently in use the viscose, before reaching thehopper, travels a long path in an intake conduit, on the inside of whichits travel obeys the laws of fluid mechanics, i.e., its flow can betheoretically likened to that of juxtaposed streams each having theirown speed, a speed that increases from the periphery to the center.Consequently, the viscose of the peripheral streams has undergone, whenit arrives in the hopper a more pronounced aging than that whichtraveledin the center. Since these streams do not overlap, this peripheralviscose is that which constitutes the surface zone, or skin, of the filmparticularly the edges.

The older, more viscous and mature viscose is of an inferior quality tothat of the new or younger and more fluid viscose which circulates inthe center. It is more heterogeneous and often carries gels'and oftenresults in weakened edges and irregular surface zone.

SUMMARY OF THE INVENTION According to the present invention the abovedifficulties are overcome in a simple and economic manner which does notrequire any major modifications of existing equipment.

In this regard the previously noted drawbacks and deficiencies of theprior apparatus and processes have feeding the hopper and connectedupstream by its larger base circumference with the inside wall of theconduit means; the truncated end or smaller base of the device isoriented downstream, with respect to the larger base, within the conduitmeans. The truncated conical extension is provided on its walls betweenthe large and small. base with openings tapered toward the back anenlarging in the direction of the current. The openings of thisexchanger, which is generally metal, are, in addition, bent toward theinside of the cone.

The exchanger according to the present invention can be connected by anyknown means with the conduit means provided it extends exactly axiallywithin the inside wall of the latter. According to one embodiment theconduit means consists of an upstream conduit and a downstream conduit.The exchanger of flow inverter is integrally formed with the upstreamconduit as a single unit. This unit at the exchanger end is insertedaxially within the downstream conduit. Of course, other embodiments arepossible. It is not particularly necessary that the shape of the frustumof the cane be rigorously geometric but it should be tapered gradually.A similar form, slightly rounded, for example, is perfectlysuitable.

The inclination of the cone frustum and the diameter of. its smallcircumference and the position, number and dimension and shape of thelateral openings can vary and depend essentially on the relative size ofthe flows that are to be exchanged.

Such flow inverter is particularly adapted for use in a process forspinning cellulose films by extrudion of viscose from a hopper into aacidic coagulation bath. The flow inverter is utilized in that prior toreaching the spinning hopper, the viscose flowing through a conduitpasses through the flowing inverter means whereby the viscose flowing onthe periphery of the conduit is diverted to the center of the conduitand a substantial portion of the viscose flowing in the center of theconduit is diverted to the periphery. In'this way it is possible toproduce a cellulose film wherein the skin and edges particularly aremade up of a new viscose with the core or center being composed of amore mature viscose.

The advantage of obtaining a cellulose film whose skin, and moreparticularly edges, are made up of a new viscose and whose core is madeup of a more mature viscoselies in the importance of the edges on theregu larity of the spinning operation and the importance of the skin onthe surface characteristics of the film.

It is, therefore, a primary object of the present invention to provideapparatus for diverting fluid flowing through a conduit as well as aprocess utilizing such apparatus, specifically in the spinning ofviscose wherein the process and apparatus eliminate disadvantages overprevious proposals.

It is a further object of the present invention to provide a flowinverting device which will bring towards the center of the intakeconduit the viscose that travels on the periphery and to move toward theperiphery a part of the most fluid viscose that travels in the center.

It is a still further object of the present invention to provide anexchanger or flow inverter in the form of a tapered pipe open at bothends and having a plurality of openings on its walls, each of suchopenings enlarging in the direction of the small, truncated base andfurther each of such openings being bent inwardly at its edges topresent a lip for inverting the flow within the exchanger.

These and other objects of the present invention will become apparentwhen read in the light of the accompanying description and drawings andthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of theexchanger device according to the present invention.

FIG. 2 is a sectional view of FIG. 1 taken along line 2--2 looking inthe direction against the flow within the exchanger device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The flow exchanger of thepresent invention, while primarily intended for use in the formation ofcellulose films having improved surface zone and edge characteristics,is capable of being adapted to any process and apparatus where it isdesired to achieve a more homogeneous product or to alter surface andedge properties. Accordingly, the accompanying drawings do not includethe hopper and other equipment associated with the extrusion andspinning of cellulose films.

The operation of the flow exchanger is shown in FIG. 1 where thedirection of flow is indicated by the arrows. As shown in FIG. 1 theconduit means consists of upstream conduit 1 and downstream conduit 3.Within upstream conduit 1 the flow of viscose consists of two distinctqualities represented by stream A flowing along the periphery and streamB flowing in the center of the conduit. This representation of the flowfollows from the laws of fluid mechanics of viscous flow within aconduit and results primarily from the increased friction of the viscoseon the conduit walls.

Integrally connected to upstream conduit 1, at the end which is insertedinto downstream conduit 3, is tapered pipe 2, which, as shown is in theform of a truncated cone having its truncated end 7 extending intodownstream conduit 3 and which forms the flow exchanger of the presentinvention. As noted earlier, it is not essential to the functioning ofthe flow exchanger that the shape of the tapered pipe 2 be as shown andhis possible, for example, for the tapering to be more gradual,'as withslightly rounded walls. A fluid tight seal between the larger basecircumference 8 of the tapered pipe 2 and the downstream conduit 3 isachieved by means of a fluid-tight ring or gasket 4. It is importantthat the two conduit sections and exchanger are in axial alignment.

Located on the walls of tapered pipe 2 between the base 8 and thetruncated end 7 are the essentially equally spaced openings 5 which arerounded and wider at the narrow end of the pipe and gradually taper backin the direction of the larger, upstream end 8. Thus, the openings 5widen in the direction of the flow of viscose. Each of the openings 5 isbordered by lips 6 bent towards and extending into the pipe.

It can be seen that the peripheral flow which follows the walls isdirected toward the center as continuous arrows A indicate, the streamswhich are perpendicular to openings 5 striking lips 6 which direct themtoward the center, whereas the central flow is directed, at least for aconsiderable fraction indicated by arrows B in broken lines, toward theperiphery of downstream conduit 3 through openings 5 of the exchanger.

The shape and taper of the openings in the inclined walls of the flowexchanger and their equally spaced position around the circumference ofthe pipe are shown in FIG. 2 which is taken looking at the exchanger inthe direction opposed to the flow.

When used in a process for spinning cellulose films by extrusion ofviscose into an acid coagulation bath through the extrusion slit of ahopper fed by an intake conduit, the flow exchanger is inserted into theintake conduit as described above.

It has been found that by using flows dyed different colors this processmakes it possible to obtain films of a continuous skin of coagulatedviscose of quality B on the surface of a core made up of a mixture ofviscose A and B, the proportion of B present in the core varyingdepending on the inclination of the cone, the dimension of its smallbase and further depending on the shape and distribution of the holesmade in its wall.

The flow exchanger of the present invention is capable of numerous otherapplications in addition to forming improved cellulose films, havingbetter homogeneity as well as improved skins and edges. It is alsosuitable for homogenizing any products or mixture of fluid products,including liquids in a molten or plastic state.

It is possible, for example, to produce mixtures made up of two or moredifferent materials injected successively at different positions in theheart of. the conduit means, when it is desired to obtain morehomogeneous characteristics such as composition, color, taste, etc. andthe successive use of several exchangers is considered to be includedwithin the scope of the present invention.

The above description is in no way intended to limit the scope of thepresent invention and it is understood that various modifications andequivalents can be used which fall within the spirit and scope of theappended claims.

What is claimed is:

1. Apparatus for diverting towards the center of conduit means a firstfluid stream initially flowing along the periphery of the conduit meansand simultaneously causing a substantial proportion of the flow of asecond fluid stream initially flowing in the center of the conduit meansto be diverted towards the periphery of the conduit means, comprising a.a downstream conduit section b. an upstream conduit section in fluidtight connection to said downstream conduit section, and

c. fluid flow inverting means axially aligned within said conduit meanscomprising a truncated conical shaped pipe connected upstream at itslarger base circumference to said upstream conduit section, thetruncated end of said conical shaped pipe extending into said downstreamconduit means, said truncated conical shaped pipe being provided with,on its walls, intermediate said larger circumference base and saidtruncated end, at least one opening tapered toward the upstream end andenlarging in the direction of the flow within said conduit means, eachof said at least one openings being bordered by lips bent towards andextending into said conical shaped pipes, thereby providing at least oneflow diverting lip within said truncated conical shaped pipe.

2. The apparatus of claim 1 wherein there are four of said openingsequally spaced about the circumference of said truncated conical shapedpipe.

3. The apparatus of claim 1 wherein said truncated conical shaped pipeis integrally connected to said upstream conduit section and saidupstream conduit section and said downstream conduit section are sealedby means of a fluid tight seal.

4. In combination with apparatus including conduit means feeding ahopper having an extrusion slit for spinning cellulose films from atleast two qualities of viscose, flow inverting means for inverting theflow of an old viscose from the periphery of said conduit means to thecenter thereof and simultaneously inverting a substantial proportion ofthe flow of a young viscose, flowing in the center of said conduitmeans, to the periphery thereof; said flow inverting means comprising atapered pipe axially aligned within said conduit means, and having anopen upstream end and an open truncated end, said tapered pipe beingconnected to said conduit means at its upstream end, the circumferenceof said tapered pipe gradually decreasing in the direction of flow fromsaid upstream end to said truncated end, said tapered pipe beingprovided with a plurality of openings intermediate said upstream end andsaid truncated end, each of said openings being tapered towards theupstream end and enlarging in the direction of the flow within saidconduit means, each of said openings being surrounded by a lipprojecting inwardly into said tapered pipe, whereby the old viscoseflowing along the periphery of said conduit means is diverted towardsthe center and a substantial proportion of the young viscose flowing inthe center is diverted towards the periphery.

5. The apparatus of claim 4 wherein said conduit means consists of anupstream pipe and a downstream pipe, said upstream pipe being axiallyconnected within said downstream pipe by a fluid tight seal and saidtapered pipe being integrally connected to said upstream pipe wherebythe truncated end of said tapered pipe extends into said downstreampipe.

6. The apparatus of claim'S wherein there are four of said openings insaid tapered pipe, said openings located approximately equally about thecircumference of said tapered pipe,

7. The apparatus of claim 4 wherein said tapered pipe is in the form ofa truncated cone.

1. Apparatus for diverting towards the center of conduiT means a firstfluid stream initially flowing along the periphery of the conduit meansand simultaneously causing a substantial proportion of the flow of asecond fluid stream initially flowing in the center of the conduit meansto be diverted towards the periphery of the conduit means, comprising a.a downstream conduit section b. an upstream conduit section in fluidtight connection to said downstream conduit section, and c. fluid flowinverting means axially aligned within said conduit means comprising atruncated conical shaped pipe connected upstream at its larger basecircumference to said upstream conduit section, the truncated end ofsaid conical shaped pipe extending into said downstream conduit means,said truncated conical shaped pipe being provided with, on its walls,intermediate said larger circumference base and said truncated end, atleast one opening tapered toward the upstream end and enlarging in thedirection of the flow within said conduit means, each of said at leastone openings being bordered by lips bent towards and extending into saidconical shaped pipes, thereby providing at least one flow diverting lipwithin said truncated conical shaped pipe.
 2. The apparatus of claim 1wherein there are four of said openings equally spaced about thecircumference of said truncated conical shaped pipe.
 3. The apparatus ofclaim 1 wherein said truncated conical shaped pipe is integrallyconnected to said upstream conduit section and said upstream conduitsection and said downstream conduit section are sealed by means of afluid tight seal.
 4. In combination with apparatus including conduitmeans feeding a hopper having an extrusion slit for spinning cellulosefilms from at least two qualities of viscose, flow inverting means forinverting the flow of an old viscose from the periphery of said conduitmeans to the center thereof and simultaneously inverting a substantialproportion of the flow of a young viscose, flowing in the center of saidconduit means, to the periphery thereof; said flow inverting meanscomprising a tapered pipe axially aligned within said conduit means, andhaving an open upstream end and an open truncated end, said tapered pipebeing connected to said conduit means at its upstream end, thecircumference of said tapered pipe gradually decreasing in the directionof flow from said upstream end to said truncated end, said tapered pipebeing provided with a plurality of openings intermediate said upstreamend and said truncated end, each of said openings being tapered towardsthe upstream end and enlarging in the direction of the flow within saidconduit means, each of said openings being surrounded by a lipprojecting inwardly into said tapered pipe, whereby the old viscoseflowing along the periphery of said conduit means is diverted towardsthe center and a substantial proportion of the young viscose flowing inthe center is diverted towards the periphery.
 5. The apparatus of claim4 wherein said conduit means consists of an upstream pipe and adownstream pipe, said upstream pipe being axially connected within saiddownstream pipe by a fluid tight seal and said tapered pipe beingintegrally connected to said upstream pipe whereby the truncated end ofsaid tapered pipe extends into said downstream pipe.
 6. The apparatus ofclaim 5 wherein there are four of said openings in said tapered pipe,said openings located approximately equally about the circumference ofsaid tapered pipe.
 7. The apparatus of claim 4 wherein said tapered pipeis in the form of a truncated cone.